This definitely needed another thread. Because maybe nobody noticed any of the 3 or 4 times you mention this in literally every single thread on this forum.

Have you noticed that you are the only person complaining about this?

But this doesn't answer why you wouldn't just start an activity?  This is what Phil is asking. 

If one understand NEAT nonexercise activity thermogenesis

, one can burn maybe up to 2000 calories more a day that One maybe not would call excercise. During a day at work and at home I may reach 3500-4000 burned calories and not doing any exercises, comuting with bike to work, runing in stairs, walking at lunch etc. I move alot and can not start 500 activitys during a day:) One need accurate HR reading during the hole day to track burned calories and in the other end I use myfitnesspal to put in my 3500-4000 calories of food. So it is very easy to build a body to that weight and bodyfat One would want. https://www.health.harvard.edu/diet-and-weight-loss/use-the-neat-factor-nonexercise-activity-thermogenesis-to-burn-calories When I can I do start an activity like bike riding but not evry time I Run in the stairs or walking.

I do understand NEAT. But people will not normally spend extended periods of time with elevated heart rates during the day when not exercising. 

Messner said:

can not start 500 activitys during a day

Sadly, hyperbole is getting in the way of reality, and has been for much of this thread and the others that have been started for exactly the same reason.

Small instances of missed elevation in HR are not going to dramatically affect caloric measurements. I would suggest that for the majority of people WHR tracking throughout the day presents a usable estimate of energy expenditure. Bounding up one or two flights of stairs is not going to change much.

If you know you are going to be doing an activity that is in excess of what you would normally do then turn on an activity.

Trying to be a voice of reason is useless when the people you are trying to reason with cannot be reasonable.

Same to you. I wrote it black at white. I take up to 16.000 step at a 8 hour work day. My Production line is about 50 meter long, and i have to feed the machine with components the hole workday. Due to that, my hr is around 100 and much higher. You would advise to wear a strap and starting an activity for the hole workday? So, as Messner stated: correct hr readings are important for the hole stats. Calories burned. The lower the heartrate, the lower the calories counted. 
Maybe my 8 hour Workday is not the normal case for you, but for every situation the hr goes up, the calories burned goes up also. But if the watch can’t count this at all day tracking, the watch isn’t able to show the daily calories burned correct.

And again: the fenix 3hr had correct readings, as well as the fenix 5x. And the fenix 6x UNTILL update after FW 3.10. 

This isn't about 24/7 hr tracking and I am familiar with NEAT, BMR and how Garmin uses these along with your selected activity class.  In my opinion, Garmin does well here.  There will always be times throughout the day where you'll get an elevated heart rate.  But these are very short periods and won't have a dramatic affect on your total calories.  This topic is about doing an activity without recording an activity.  Yes, it would be quite ridiculous to record yourself running up or down a flight of stairs.  It's just as ridiculous as going on a run, bike ride, cardio workout, etc. and not record it.  Wouldn't you agree?  Especially after you've determined your watch doesn't record well when your not in an activity.

Please read about NEAT. To understand me You have to track burned calories and track calories that You intake and then track bodyfat and weight and waist etc and that for many years. My TDEE at home is only maybe 2000 calories but because I understand NEAT I am rather active during the day with elevated HR to burn more  so I Increase from about 2000 calories to about 3500-4000 calories. According to Garmin my Calorie goal is only 1920 calories but My active calories is always over 1000 calories. At work I walk at least 10 000 steps and I run or walk between 40-70 floors a day, that is many stears and I never use the elevator and I do carry heavy stuff during work :) That is NEAT in action:)

Sorry, but Messner is right.

bluefish said:

I take up to 16.000 step at a 8 hour work day. My Production line is about 50 meter long, and i have to feed the machine with components the hole workday. Due to that, my hr is around 100 and much higher.

In all seriousness and I'm not trying to be rude, but do you have a medical condition that causes you to have an elevated HR?  I'm doing the math here.  If you're getting 16,000 steps a day over an 8 hr period why would your HR be around 100 and much higher?  I'm in good shape, but far from being in great shape.  I also work 8 hr shifts, average 12,000 steps and rarely exceed 100 bpm or higher let alone for 8 hours straight.